The present invention is related to a constant speed controlling device and method, and especially to a constant speed controlling device and method for automatically operating an electric vehicle at a selectively designed speed.
In recent years, more and more vehicles or electric vehicles are provided with a constant speed controlling device which can operate vehicles automatically at the constant speed after a user sets a desired speed. However, the constant speed function of an electric vehicle in the market is to only fix the output power of motor regardless of externally variable factors which may also affect the running speed of the vehicle, for example, wind direction, slope of road surface, and weather, etc. Furthermore, there is no feedback control signal generated from wheels to attain the purpose of actually operating vehicles at a constant speed.
Therefore, it is desirable to develop a constant speed controlling device and method to be applied in the electric vehicles so as to provide vehicle operators with comfortable and convenient feeling and to save the electric consumption of storage battery used for the electric vehicle.
An object of the present invention is to provide a constant speed controlling device and method to be applied in the electric devices or vehicles which needs to be operated automatically at constant speeds.
Another object of the present invention is to provide a constant speed controlling device and method adapted to be used with an electric vehicle to provide vehicle operators with comfortable and convenient feeling and to save the electric consumption of storage battery for the electric vehicle.
According to the present invention, the constant speed controlling device for automatically operating an electric device driven by a prime mover at a selectively designed speed includes a detector for detecting a running speed of the electric device to generate a feedback signal; a controller electrically connected with the detector for converting the feedback signal to a digital signal to be compared with a predetermined value representative of the selectively designed speed so as to generate a control signal; and a driving device electrically connected with the controller for adjusting an output power of the prime mover and driving the prime mover corresponding to the control signal so as to allow the electric device to run at the selectively designed speed.
Certainly, the electric device can be an electric vehicle or a mowing machine, for instance, an electric bicycle, an electric motorcycle, an electric automobile, an electric truck, and a skateboard, etc.
Preferably, the prime mover is a motor, and the prime mover and the constant speed controlling device are powered by a storage battery.
In accordance with one aspect of the present invention, the controller includes a microprocessor or a microcomputer. The controller further includes a register for storing the predetermined value and the digital signal and an operator electrically connected with the register for comparing the digital signal and the predetermined value to determine an output state of the control signal. The control signal is a pulse width modulation (PWM) signal, wherein the duty cycle of this pulse width modulation signal is increased by the operator when the running speed of the electric device is less than the selectively designed speed, but the duty cycle of the pulse width modulation signal is decreased by the operator when the running speed of the electric device is greater than the selectively designed speed.
In addition, the constant speed controlling device further includes a control switch electrically connected with the register for actuating the controller to memorize the running speed of the electric device in the register to be compared with the selectively designed speed. Preferably, the control switch is a constant speed control button for allowing a user to optionally select the desired speed.
Moreover, the present invention also provides a constant speed controlling method for automatically operating an electric device driven by a prime mover at a selectively designed speed. This method includes the steps of a) providing a feedback signal corresponding to a running speed of the electric device; b) converting the feedback signal to a digital signal to be compared with a predetermined value representative of the selectively designed speed so as to generate a control signal; and c) adjusting an output power of the prime mover and driving the prime mover corresponding to the control signal so as to allow the electric device to run at the selectively designed speed. The output power of the prime mover is increased in the presence of a resisting force to allow the electric device to run at the selectively designed speed, but the output power of the prime mover is decreased when the resisting force is eliminated so as to save the electric consumption of the storage battery.
The resisting force comes from the wind direction, wind force, weather, slope of road surface and paving condition, etc.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which: